Power actuator



Aug. 23, 1932.

c. s. BRAGG ET AL POWER ACTUATOR Original Filed Jan. 5, 1925 3Sheets-Sheet l Til QJINIVENTORS BY A:$ORNEY 7 Patented Aug. 23, 1932UNITED STATES "PATENT OFFICE ems s. BRAGG, or PALM 3mm, INDIANA,ASSIGNORS c ISLAND CITY, NEW YORK, A CORPORATION BEACH, FLORIDA,

TO BRAGG-KLIESRATH CORPORATION, LONG AND vroron w. xmnsmrn, or son'rn OFNEW YORK POWER ACTUATOR Orlghml application fled January l5, applicationillustrate several embodiments of thesame,

I States filed December 22, 1923 selected by us for purposes ofillustration, a

and the said invention is fully disclosed in the following descriptionand claims.

This application is a division of our former application filed January5, 1925, and given Serial No. 506.

Our invention relates to a power actuator,

adapted especially for use in connection with automotive vehiclespropelled by an internal combustion engine, and most convenientlyoperated by suction from a suction passage of the engine between thethrottle valve and the engine cylinder, or cylinders, as for example, bymeans of a connection with the intake manifold of the engine. In ourprior application for Letters Patent of the United c Serial No. 682,346,issued as Patent No. 1,79%,853, March 24, 1931, wehave disclosed a poweractuator of this general type connected with the intake manifold of theinternal combustion engine by means of a pipe or passage in which arelocated an adjustable regulating valve or other restricting means, acheck valve, and a storage space, cylinder, a double acting pistontherein, and reversing valve mechanism for applying differentialpressures on opposite faces of the piston, and said actuator beingcombined with a foot lever, or other operator opera ed part, and with abrake mechanism or other part to be actuated in such manner that thelatter can be operated by the actuator under the control of the footlever while the operator "may add his physical power to the power, ofthe actuator when desired, or in case of failure of the actuator, maypositively operate the actuated part by physical power appliedto thefoot lever, or other operator operated part. i

The regulating valve or other restricting device prevents such largevolumes of air being drawn into the intake manifold as to be likely todilute the explosive charges passing therethrough, so as to stall theengine when idling while the storage space or storor tank, andcomprising a age tank provides a large space in which a partial vacuumor rarification s maintained .at all times, while the englne is running,by withdrawing the air therefrom in comparatively small quantities, andinsures the in- 1925, Serial it'o. 506. Benewed February 15, 1982.Divided and this filed August 30, 1926. Serial No. 132,365.

stantaneous withdrawal of the necessary amount of air from the actuatorcylinder when the reversing valve mechanism is moved to open position,to insure the instantaneous and effective operation of the actuator.

According to our invention, we dispense with any extraneous storagespace or storage tank in the suction line extending to the intakemanifold exterior to the actuator cylinder, and maintain a condition ofpartial vacuum or rarification within the actuator cylinder itself, onboth sides of the piston, which is made to supply the necessary storagespace. Thereby we obtain a number 0 important and advantageous resultsin the construction, installation and operation of the power actuator.In the first place, the tank, which is a bulky element, is entirely doneaway respondingly simplified and rendered less expensive. As a partial,vacuum is maintaine within the actuator. cylinder on both sides of thepiston therein when the device is in normal or inoperative position,when the reversing valve mechanism is moved into a position to'efiectthe operation of the actuator,

with and the construction is cor,- Y

one end of the cylinder on one side of the and the immediate result isthat the atmospheric air rushes into the end of the cylinder" to whichit is admitted, and eflfects the operation of the piston in the desireddirection Q and to'the desired extent without any appreciable quantityof air being actually withdrawn from the cylinder and admitted to theintake manifold or other suction means, thereby eliminating the drop inthe suction or rarlfication, which would result were the cylinder fullof air and this air admitted during the application, of the brakes. Themaximum suction isv therefore immediately available. The restrictingvalve properly adjusted ,,hicles such as automobiles, trucks and motorbuses, for example, as when the brake is applied the actuator isoperated without any material admission of air to the intake manifoldand therefore without any possibility of injuriously affecting theexplosive mixture or of stalling the engine, and when the valvemechanism is reversed to effect the release of the brakes, by operatingthe piston in the opposite direction, the atmospheric air admitted forthe purpose of obtaining the previous application of the brakes can begradually withdrawn to the intake manifold, under the control of theregulating valve, so as to prevent interference with the operation ofthe engine, while securing the effective release of the brake mechanism.If the motor should 'stall due to the admission of this air when thebrakes are being released, it would be a matter of far less importancethan the stalling of the motor when the brakes are being applied. It isnot so important that the movement of the piston in a direction torelease the brakes shall be as rapid as the movement of the piston inthe direction to apply the brakes. As a matter of fact, a very slightmovement of the piston in the direction to release the brakes would besutlicient to release them, and for this reason continued applicationand releasing of the brakes without allowing the piston to come to theat rest position may be elfected with comparatively small amount of airbein drawn into the intake manifold, and the piston may be permitted toreturn to its normal position after an application of the brakes moreslowly than it would be desirable to have it moved in the oppositedirection. Furthermore when the piston comes to the at rest positionafter an application of the brakes, there is a partial vacuum in therear of the cylinder. Therefore, the only air to be exhausted is theamount admitted-to the forward end of the cylinder to effect thereleasing of the-brakes, which is considerably less than the totalamount of air that could be contained in the cylinder, were it not forour invention, which continually keeps at least one end of our cylinderunder vacuum, the total amount of air in the cylinder would have to beexhausted after each operation of the brakes.

ur invention therefore enables us to simplify and decrease the cost ofthe apparatus, and at the same time insures the most eflicient operationof the actuator without prejudice to the continuous and eilicientoperation of theinternal combustion engine from the suction passage ofwhich the necessary power or suction for the operation of the actuatoris derived.

In our former application above referred to, these featuresare broadlyclaimed together with one of the specific embodiments for carryingourinvention into effect, and

the present application is directed to certain other specificembodiments for carrying the invention into eflect disclosed in ourPI'QVl-w ous application above referred to, but not specifically claimedtherein, but which are specifically claimed in this application.

Referring to the accompanying drawings,

Fig. 1 represents a diagrammatic View of an installation in which ourimproved power actuator is connected with the internal combustion engineof an automotive vehiclefor the operation of thebrake mechanism thereof.

Fig. 2 is an enlarged sectional view-illustrating one form of ourimproved actuator having one embodiment of our present inventiontherein.

Fig. 3 isan enlarged sectional view of the power actuator shown in Fig.2, portions being broken away.

Fig. 4 is a partial-sectional view of our improved power actuatorshowing another modification of our present invention embodied therein.

Fig. 5 is an enlarged sectional view of our power actuator showing stillanother modi-. fication of our present invention embodied therein.

Fig. 6 is a partial sectional view of a por-' tion of the actuatorillustrating a slight mod ification of the construction shown in Fig. 5.

In Fig. 1 of the accompanying drawings, We have shown digrammatically aninstallation suitable for use in an automotive vehicle in which one ofour improved actuators is shown as interposed in the connections between afoot lever, 88, and brake mechanism for the vehicle,diagrammatically represented at 70, 71 and 72, indicating a brake drum,brake band and brake lever. The

brake mechanism will be provided withthe usual retracting means,indicated diagrammatically in the drawing, by the spring, 74.

60 represents an internal combustion engine for propelling the vehicle,and provided with an intake manifold, indicated at 61, and communicatingwith the carburetor, 61?, to which is connected a pipe, 62, between thethrottle valve indicated at 61 and the engine cylinders, in which pipeare located preferably an adjustable regulating valve, or restrictingvalve, 64, a check valve, 65, and a vent valve, 67, normally closed andopening outwardly. The pipe, 62, commuof our improved 1 eating with thereversing valve mechanism.

The sleeve, 320, is connected by a link, 85, with the foot lever, 88,which is provided with the usual retracting spring, 89, and the pistonrod, 305, of the actuator is connectedv by a link, 73, with the brakelever, 72.-

In Figs. 2 and 3, we have shown one form actuator embodying our presentinvention. In this figure, 301, represents the actuator cylinder closedatboth ends by heads, 302, connected by bolts indicated at 302*, in Fig.1, or otherwise. 303 represents the double acting piston provided withoppositely disposed gaskets, 304. 305

represents a hollow piston rod which extends through a stufiing box,306, in one end of the cylinder, and is connected at its inner end withthe piston, 303. The hub, 310, of the piston is provided with two valvechambers, 311 and 312 respectively, each of which is provided with twovalve seats preferably conical and coaxial with the axis of the piston.The valve chamber, 311, is provided with seats, 313 and 314, and thevalve chamher, 312, is provided with valve seats, 315 and 316. Thepiston hub is provided with an outlet chamber or suction chamberindicated at 317, which communicates with each of the valve chambersthrough the valve seats, 314 and 315. The piston hub is also providedwith a higher pressure chamber, 318, in this instance communicating withthe atmosphere and with the valve seat, 316, and by a lateral passage,319, with the valve seat, 313. The valve actuating part, in thisinstance, a hollow sleeve, 320, passes through a stufiing box, 321,in'the cylinder head at the opposite end of the cylinder from thestuffing box, 306, the said sleeve extending longitudinally through thepiston hub and valve chambers, and through the hollow piston rod, 305,and being longitudinally movable to eflect the operation of thereversing valve. The valve s'leeve may be made conveniently in twoparts, 320 and 320 if desired, and as herein shown is provided with apair of oppositely disposed poppet valves in each valve chamber, thesaid valves being preferably formed of molded. rubber and frictionallyengaging the sleeve, so that the sleeve may move through the valve whileforming an air-tight joint therewith. The valves are in dicated at 340,341, 342 and 343, the valves 341 and 342 being suction valves, and thevalves, 340 and 343 being air inlet valves.

The valves are yieldingly held in engage-' ment with their seats,preferably by a yielding cushioning device. interposed between the pairsof valves, and indicated at 350. The actuating sleeve is provided withsuitpipe having a flexible able means for opening one valve of each pairwhen the sleeve is moved in either direction. In this instance, thesleeve is shown provided with a collar, 322,1ocated between the suctionvalves, 341 and 342, and adapted to operate either of the said valves.and the sleeve is also provided with collars, 331 and 332, mounted onthe valve sleeve outside of the air inlet valves, '340 and 343respectively, for operating said valves. Communication between thesuction pipe, 62, and the suction chamber, 317, is effected in thisinstance? through the hollow valve sleeve, which is provided with afitting, 326, at its outer end, to which the pipe, 62, is connected, andlateral passages, 324, are formed in the collar,

322, to connect the interior of the sleeve with "the suction chamber. 4

The specific details of the poppet valve mechanism herein shown anddescribed form no part of our present invention, as the same isdisclosed and claimed in our former application for Letters Patent oftheUnited States, filed November 22, 1924, and given Serial No. 751,481.

In the form of our invention illustrated in Figs. 2 and 3, the centralcollar 322, in the vacuum chamber, 317, which actuates the suctionvalve, is so located with respect to a stop, in this instance formed bya shoulder, 326, on the fitting, 326, which engages the adjustablefollower, 321*, of the stuffing box, 321, when the parts are in normalor ofi position, that when the piston is arrested by the engagement ofits hub with the opposite end of the cylinder, the valve actuatingsleeve, 320, will hold the suction valve, 342, slightly off its seat, asshown in Figs. 2 and 3, thereby placing the cylinder in rear of thepiston in communication with the suction chamber through a port orports, 335, which connect the valve seat, 315, with that portion of thecylinder. The other suction valve, 341, being seated, the ports, 334,which connect its valve seat, 314, with the forward portion of thecylinder are closed. In order to insure the evacuation of the portion ofthe cylinder on the other side of the piston, the main body of thepiston is in this instance provided with an aperture or passagetherethrough indicated at 342 having a valve seat, 342", at the endadjacent to the forward face of the piston, to receive a valve, 342,normally held in closed position by a spring, 342 engaging the valvestem, 342. The valve stem, 342, projects from the rear face of thepiston (to the right in Figs. 2 and 3) sufficiently to engage a fixedportion of the cylinder, as the the piston, and as the valve, 342, iscracked the air introduced into the cylinder on the forward side of thepiston to insure its retraction, or return to normal position, will beexhausted as soon as the piston comes to rest, thus maintaining partialvacuum at all times within the cylinder on both sides of the piston whenthe parts are at rest and the engine is in operation.

It follows from this construction that as soon as the engine is startedthe suction produced in the intake manifold will exhaust the, air fromthe cylinder of the actuator on both sides of the piston. If now it isde sired to apply the brakes, the foot lever is actuated to move thesleeve, 320, in the direc-' tion of the arrow in Fig. 2, therebypermitting the suction valve, 342, to close, and subsequentl opening thesuction valve, 341, and

the air inlet valve, 343; This connects the cylinder forward of thepiston with the suction chamber, 317, and admits atmospheric air in rearof the piston, moving the piston forward in a direction to apply the.brakes, but no appreciable amount of air will be drawn into the intakemanifold through the pipe, 62, as the portion of the cylinder forward ofthe piston is already exhausted. The forward movement of the piston willfollow any extent of the forward movement of the brake lever, 88, andwhen the movement of the brakelever stops,-the piston will continue tomove forwardly until the suction valves, 341, and air inlet valve, 343.,closed, so as to hold the piston and brakes as applied. Where continuedapplications of the brakes are desired, a slight release of the footlever producing a slight rearward movement of the valve sleeve will openthe suction valve, 342, without opening the air inlet valve 340 andconnect the cylinder in rear of the piston with the suction passage, 317thus withdrawing portions of the air admitted for the piston stroke andproducing a partial or entire equalization of pressures on oppositesides of the piston, which will instantly permit the brakes to relievethemselves, under the action of their retracting means, as the spring,74, and slightly retract the piston. A slight forward moyement of thepedal lever will again admit air in rear of the piston, and'connect thecylinder forward of the piston with the suction chamber, and a number ofsuccessive applications of the brake can be made without admittingmaterial quantities of air into the intake manifold. When the footlever, 88, is released, the retracting spring, 83, will move the valvesleeve, 320, in a direction opposite that indicated by the arrow in Fig.2, and the suction valve, 341, will be forced to its seat by thecushioning device, and the reversed movement of the sleeve, 320, underthe action of the retracting spring, 89, of the foot lever, will en thesuction valve, 342, connecting the cy 'nder in rear of the piston withthe suction chamber, and the air inlet valve, 340, will be openedadmitting atmospheric air to the cylinder forward of the iston throughthe opening, 333, controlled y said valve, thus returning the piston tonormal osition, illustrated in Figs. 2 and 3, the piston being arrestedby engagement with the end of the cylinder, and the valve actuatingsleeve being arrested by the engagement of the shoulder, 326, with thefollower, 321", and the auxiliary valve, 342, being opened by theengagement of its stem with the head of the cylinder. The suctionchamber, 317, will therefore be in communication with the cylinder inrear of the piston by reason of the unseated position of the valve 342,and will also be connected with the cyhnder forward of the piston by theauxiliary passage, 342, equalizing the pressures on opposlte sides ofthe piston, and the air previously admitted, to effect the reversemovement of the piston, will be exhausted from the cylinder producingrarification on both sides of the piston. -The exhaustion of air fromthecylinder, therefore, only takes place during and after the return strokeof the piston, and the air exhausted from the cylinder is de liveredgradually to the intake manifold by properly regulating the restrictingvalve, 64, in the pipe, 62, so that the operation of the engine will notbe interfered with, and the eduction of the air may be retarded as muchas desired, as the first movement of the piston rearwardly will relievethe pressure of the brakes, and it'is not important that the pistonshould move rearwardly as uickly as it moves forwardly to apply therakes.

The withdrawal of the air may, therefore, be

distributed over a great or less period of time, according to theadjustment of the valve, 64, so as to avoid the undue dilution of theexplosive charges or the feedin of too small an amount of hydrocarbonuel, and the piston is left submerged in vacuum and ready for immediateand effective operation to apply the brakes at any moment. As the degreeof suction in the suction passages of the engine varies from time totime, we

interpose the check valve, 65, in the pipe,

62, sothat after the cylinder is subjected to the greatest amount ofsuction, the condition of rarification so produced will remain, and asthe brakes are usually operated at intervals, the greatest possiblerarificationwill ordinarily exist in the cylinder of the actuator at alltimes, ready to effective apply the brakes in the manner beforedescribed.

We prefer to connect the valve actuating sleeve, 320320=, with thepiston by means providing for a limited amount of lost motion,sufficient to permit the operation of the valves, so that after thislost motion ist-aken up, the physical power of the operator can bedirectly applied to the piston and the brake mechanism connectedtherewith, to

442. The recess, 442*, is

motion permitting the movement instance, as shown in Fig.

enable the operator to add his physical force to that of the actuator,or to operate the brakes by his physical force 'alone if the powershould fail for any reason, the lost of the valves in any case, andserving when power fails to vent the cylinder. In the present 2, thesection, 320 of the valve sleeve is provided with arecessed portion,320*, and a collar, 320, and a piston rod, 305 is in this instanceprovided with, set screws, 305 extending into said recess (or recesses)320', so that when the sleeve is moved forward by the foot lever to;apply the brakes, and the piston has followed, applying the brakes tothe full capacity of the actuator,,the operator may be pushing the footlever, 88, further forward until the rear edge of the recess, 320*,engages the screws, 305 apply his physical force to the piston and brakemechanism in addition to the power of the actuator. It also follows fromthis construction that the operator, should the power of the actuatorfail, may apply the brakes directly by his physical power, the firstforward movement of the valve actuating sleeveiwill set the valves so asto vent the cylinder forward of the piston and admit air in the rear ofthepiston, to permit this movement. On the release of the foot lever,the retracting spring, 89, will shift the valve sleeve rearwardly, so asto vent the cylinder (in case of failure of power), and the forward endof the recess, 320", will engage the set screws and move the pistonrearwardly to release the brakes and restore the parts to or position.

Instead of locating the additional valve in the piston itself, it may belocated irij'the head of the cylinder and opened by the piston when itreturns to its normal position to establish a communication between thetwo ends of the cylinder on opposite sides of the piston. Such aconstruction is illustrated in'Fig. 4, in which the corresponding partsare given the same numerals as those in Figs. 2-and 3, with the additionof 100, to avoid unnecessary description. In this instance the valve,442, is held off its seat when the parts are in'normal position, in'thesame manner as indicated and previously des ribed with reference toFigs. 2 and 3. In thi s instance the head, 402, of the cylinder isprovided with passages indicated at 442*, communicating with a recess,442, and controlled by a valve, 442, the stem. 442", of wh ch projectsinto the interior of'the cylinder far enoughto be struck by the hub ofthe piston when it returns to its normal or retracted position, so as toopen the valve, connected by a indicated at 442 with the by-pass orpipe,

the cylinder, thepipe being opposite end of "conveniently carriedthrough one-of the hollow bolts, 402 connecting the heads of thecylinder. The efiect of this construction will be, as before described,to place both ends of the cylinder onopposite sides of the piston incommunication with the vacuum chamber, 417, when the parts return to andare in normal, or retractedposition, so as to maintain a partial vacuumwithin the cylinder on both sides of the piston at all times.

In Fig. 5, we have shown a further modification of the invention, inwhich the desired results are accomplished without interfering with thenormal operation of the valve mechanism, that is to say, in which allfour of the valves of the reversing valve mechanism are permitted tofirmly seat when the parts are in normal position. In this figure, thesimilar parts to those previously described, are given the samereference numerals as in Figs. 2 and 3, with the addition of 200,toavoid unnecessary description, an will be identical with thosepreviously described with reference to Figs. 2-and 3. In this instancethe head, 502, of the cylinder, is provided with a passage, or passages,542, communicating with a recess, 542, in which is located a valve seat,542, engaged by a movable valve, 542, which valve'during the applicationof the brakes closes communication between the recess, 542, and theinterior of the cylinder on both sides of the piston.

dss

The valve is operated by a ring, 542, prothe opening of the valve, 542.The valve seat 542, is connected by a flexible pipe, or

tube, 542 with the suction pipe, 562, independent of its connectionswith the reversing valve mechanism, through the hollow valve sleeve 520,and the valve seat, 542, is also connected by a pipe, 542 with thecylinder on the forward si'deof the piston in the same manner asillustrated in Fig. 4. From this construction it will be noted that whenthe piston moves forward the valve is seated by its frictionalengagement with the piston rod, and may be maintained on its seat by alight spring, 542. en the piston returns to its normal position,movingto the right in Fig.5, the hub of the piston will engage the pins, 542,and open the valve, 542 thereby establishing communication between theauxiliary exhaust pipe, 542, and both ends of the cylinder, exhaustingthe air from the cylinder on the forward side of the also maintainingthe partial vacuum 1n the cylinder at the rear of the piston, producedin returning the piston to its normal position. In Fig. 6, wehave shownanother'slight modification ofthe device "illustrated in Fig. 5, Fig. 6,being a partial sectional view in which the parts illustrated in Figs..2and 300 added. 11 th's figure the auxiliary valve,

tobe

piston, and p instead of being located centrally ofvthe cylinder head,practically within the stuffing box, as illustrated in Fig. 5, islocated in a separate fitting, indicated at 644, pro 'vided with athreaded portion, 445, which is screwedv into an aperture in the head,602, of the cylinder. This fitting is provided with a passage, 642,communicating with the interior of the cylinder and controlled by anauxiliary valve, 642, normally held seated by spring, 642", secured inposition by a suitable cap, 642, and the fitting is also provided with athreaded aperture to receive a flexible suction pipe, 642, communicatingwith the main suction pipe, as described with reference to Fig. 5, andthe fitting is also provided with a pipe, 642, which communicates withthe other end of the cylinder on the opposite side of the piston. Theauxiliary valve, 642 is provided with a valve stem, 642, which projectsinto the cylinder in position to be engaged bythe piston when the latterreturns to its normal position, so as to open the valveandi establishcommunication between the vacuum pipe or suc- ,tion pipe leading to themanifold of the en gine, and both ends of the cylinder, and therebymaintaining a partial vacuum within the cylinder on both sides of thepiston in exactly the same manner as previously described, withreference to Fig. 5.

It will be noted that in all the forms of apparatus herein shown, for.the purpose of illustrating various embodiments of our invention, all ofwhich are capable of use in the general installation illustrated in Fig.1, a vacuum is continuously maintained in the actuator cylinder on bothsidesof the piston when it is in its normal position and the engine isin operation, so that the cylinder itself acts as a storage space, andno ,additional tank or other extraneous storage space is required. Inall of these forms of our invention, there is no storage tank and 4after the engine is started the air in the actuator cylinder and thepiping leading to the intake manifoldor other suction passage of theengine is exhausted, when the apparatus is in itsmost eifective andoperative condition, a partial vacuum existing in the cylinder onbothsides of the piston.

The check valve, 65, shown in Fig. 1, and interposed in the suctionpipe, insures the exhaustion of the cylinder on both sides of the pistonto the greatest extent permitted at any time by the operation oftheengine by the manipulation of the throttle valve, while the vent valve,67*, shown in Fig. 1, provides for the venting of the cylinder shouldthe motor stop, or the suction fail at any time, and should it becomenecessary for the operator to apply the brakes by physical power.

What we claim and desire to secure by Letters Patent is of suction,means acting on said valves when the piston is in retracted position forconnecting the fportion of the cylinder on one side only 0 the pistonwith said suction means,.said actuator being provided with an auxiliarypassage for connecting said portion of the cylinder with the portion ofthe cylinder on the opposite side of the piston, when the piston is inretracted position.

2. In a power actuator, the combination of a cylinder closed at bothends, a double acting piston in said cylinder, reversing valve mechanismincludin a suction chamber, passages connecting sai chamber with thecylinder on both sides of the piston, an air inlet, passages connectinsaid air inlet with the cylinder on both si es of the piston, andcontrolling valves for said passages, means for connecting said suctionchamber with a source of suction, means acting on said valves when thepiston is brought to retracted position .for connecting the portion ofthe cylinder on one side only of the piston with said suct on means,said actuator being provided with valve controlled means for connectingsaid portion of the cylinder with the portion of the cylinder on theopposite side of the piston, when the piston is in off position.

3. In a power actuator, the combination of a cylinder closed at bothends, a double acting piston in said cylinder, reversing valve mechanismincluding a suction chamber, passages connecting said chamber with thecylinder on both sides of the piston, an air inlet, passages connectingsaid inlet with the cyliner on both sides of the piston, and con-,

trolling valves for said passages, means fol connecting sa1d suctionchamber with a source of suction, means acting on said valves whenopposite side of the pistomand an auxiliary valve for said passagecarried by the piston and constructed to be opened when the piston ismoved to its ofl or retracted position.

of a cylinder closed at both ends, a double acting piston in saidcylinder, reversing valve mechanism includin a suction chamber, passagesconnecting sai chamber with the cylinder on both sides of. the piston,an air inlet,

4. In a power actuator, the combination o cylinder on both sides of thepiston,

25. ed position,

passages connectin' said inlet with the cylinder on both sides thepiston, suction valves and inlet valves for said passages, means forholding and the other seated when the piston is in retracted or offposition, to connect the suction chamber with the cylinder on one sideof the piston only, said actuator being provided with means forconnecting the said portion of the cylinder with the portion of thecylinder on the other side of the piston, when the piston is inretracted position. 7

5. In a power actuator, the combination of a cylinder closed at bothends, a double acting piston in said cylinder, reversing valve mechanismincludin a suction chamber, passagesconnecting sai chamber with thecylin der on both sides of the piston, an air inlet, passages connectingsaid air inlet with the suction valves and inlet valves for saidpassages, means for normally holding said valves seated, means forholding one of said suction valves unseated when the iston is inretractto connect the portion of the cylinder on one side of the pistonwith the suction chamber, said actuator being provided with an auxiliarypassage for connecting said portion of the cylinder with the portion ofthe cylinder on the opposite side,

of a cylinder maintained in open condition when the said suction valveis unseated, and the piston is in its off or retracted position.

6. In a power actuator, the combination closed at both ends, a doubleacting piston in said cylinder, reversing valve mechanism including asuction chamber, passages connecting said chamber with the cylinder onboth sides of the piston, an air inlet, passages connecting said airinlet with the cylinder on both sides of the piston, suction valves andinlet valves for said passages, 'means for holding one of said suctionvalves unseated, to connect said suction chamber with the cylinder onone side of the piston when the piston is in retracted position, saidactuator being provided with a passage independent of the passagescontrolled by the suction and inlet valves for connecting said portionof the cylinder with the portion of the cylinder on the other side ofthe piston, an auxiliary valve for said passage, and means brought intooperation when the piston is in its retracted position, for opening saidauxiliary valve.

7 In a power actuator, the combination of a cylinder closed at bothends, a double acting piston in said cylinder, reversing valve mechanismincluding a suction chamber, passages connecting said chamber with thecylinder on both sides of the inlet passages connecting said inlet withthe cylinder on both sides of thepiston, suction valves and inlet valvesfor said passages, means for holding one of said suction valves one ofsaid suction valves unseated piston, an air retracted position,

unseated, to connect said suction chamber with the cylinder on one sideof the piston when the piston is in retracted position, said actuatorbeing provided with a passage.in-

dependent of the passages controlled by the reversing valves forconnecting said portion of the cylinder with the portion of thecylinderon the other side of the piston, an auxiliary valve for saidpassage, said auxiliary valve being constructed to be opened bysaidcylinder when the piston comes to 7 rest in its retracted or offposition.

8, In a power actuator, the combination of a cylinder closed at bothends, a double acting piston in said cylinder, reversing valve mechanismin said piston, means for connecting said reversing valve mechanism witha source of suction and and operator operated means for said reversingvalve mechanism, means acting on 'the' valve mechanism for connectingthe cylinder on one side of the piston wlth the source of suction whenthe piston is in retracted or 0 position, said actuator being providedwith a passage for connecting the said portion of the cylinder with theportion of the cylinder on the opposite side of the piston, when thepiston is in retracted position. 9. In a power actuator, thecombinationoif a cylinder closed at both ends, a double actingpiston insaid cylinder, reversing valve mechanism in said piston, means forconnecting said reversing valve a source of suction and with theatmosphere, and operator operated means for said re-- versing valvemechanism, the valve mechanism for connecting the cylinder on one sideof the piston with the source of suction, when the piston is inretractedor 0E position, said actuator being provided with a passage forconnecting the said porniechanism with with the atmosphere,

means acting on tion of the cylinder with the portion of the cylinder onthe opposite side of the piston, an auxiliary valve for controlling saidpassage, and means for opening said auxiliary her and suction passagesextending therefrom to the'cylinder on both sides ofthe piston, an airinlet passage, and passages for connecting said air inlet with thecylinder on both sides of the piston,

air inlet passages, yielding means normally holding said valves seated,and a vacuum producing means connected with said vacuum chamber, ofmeans forholding one of said suction valves and inlet vvalves forcontrolling said suction and suction valves'unseated when the piston isin the piston being provided therethrough, maintained in with a passager to'connect the portions of the 1 open condition both sides of thepiston, suction valves and inlet valves for controlling said suction andair inlet passages, yielding means normal- 1y holding said valvesseated, and a vacuum producing means connected with said vacuum chamberof means for'holding one of said suction valves unseated when the pistonis in retracted position, the piston being provided with a passagetherethrough, for connecting the portions of the cylinder on oppositesides of the piston, an auxiliary valve for controlling said passage,and means for opening said auxiliary valve when the piston is inretracted position.

12. In a power actuator, automotive vehicles provided with an internalcombustion engine havinga suction passage, the combination with acylinder closed at both ends, a double acting piston in said cylinderconnected to the part to be operated, reversing valve mechanismincluding a suction chamber, passages connecting said chamber with thecylinder on both sides of the piston, and air inlet'passages connectingsaid inlet with the cylinder on both sides of the piston,controlling-valves for said passages, yielding means for normallyholding said controlling valves seated, ofasuction pipe for connectingsaid suction chamber -with'the suction passage-of the engine, means forholding one of said 'valves unseated when the piston is in retractedposition to connect the portion of the cylinder on one side of thepiston with the suction chamber, said actuator being provided with anauxiliary passage for connecting the portions offlthe cylinder onopposite sides of the piston, an auxiliary valve for controlling saidauxiliary passage, means for seating the auxiliary valve, means foropening the auxiliary valve when the piston is in retracted position,and an operator operated part for actuating said reversing valvemechanlsm. I x a k 13. In a power actuator, automotive vehicles providedwith an internal combustion engine having a suction passage, thecombination with a cylinder closed atboth ends, a double acting pistonin said cylinder connected with'the part to be actuated, reversing valvemechanism including a suction chamber,'passages connecting said chamberwith the cylinder on both sides of the piston, and air inlet passagesconnecting said inlet with the cylinder on both sides ofthe piston,

controlling valves for said passages, yielding means for normallyholding said controlling valves seated, of a suction pipe for connectingsaid suction chamber with the suction passage of the engine, means forho1ding one of said valves unseated when the piston is in retractedposition, to connect the portion of the cylinder on one side of thepiston with the suction chamber, said piston being provided with anauxiliary passage therethrough connecting the portions of the cylinderon opposite sides of the piston, an auxiliary valve for controlling saidpassage, yielding means for seating said auxiliary valve, means foropening said auxiliary when the piston is brought to retracted position,and

an operator operated part for actuating said a higher pressure fluid onone side of the piston to 15. I motive vehicles provided with aninternal combustion engine having a throttle controlled suction passage,the combination with produce a power stroke thereof.

a part to be actuated, an actuator for said,

part including a cylinder and a piston movable th'erein, passages forconveying motive fluid to and from said cylinder to actuate said piston,and an auxiliary passage adapted to connect both ends of said cylinderto suction for equalizing pressure on both sides of the n vacuum brakemechanism for autopiston when the piston is brought to retractedposition.

16. In vacuum brake mechanism for automotive vehicles provided with aninternal combustion engine having a throttle controlled suctionpassage,'the combination with a part to be actuated, an actuator forsaid part including a cylinder and a piston movable therein, a suctionpipe connecting said cylinder and said source of suction, a highpressure inlet, passages connecting said suction pipe and said higherpressure inlet to said cylinder, and an auxiliary passage connecting theportions of the cylinder to suction on both sides of the piston when thepiston is brought to retracted position.

17. In vacuum brake mechanism for automotive vehicles provided with aninternal combustion engine having a throttle controlled suction passage,the combination with a part tobe actuated, an actuator for said partlncluding a cylinder and a piston inovable therein, a suction pipeconnecting said cylinder and said source of suction, a hig pressureinlet, passages connecting said suction pipe and said higher pressureinlet to 5 said cylinder, and an auxiliary passage through said pistonconnectin the portions or the cylinder on to suction oth sides of thepiston when the piston is brought to retracted position.

10 18. In vacuum brake mechanism for automotive vehicles provided withan internal combustion engine having a throttle controlled suctionpassage, the combination with a part to be actuated, an actuator forsaid 15 part including a cylinder and a. piston movable therein, asuction pipe connecting said cylinder and said source of suction, a highpressure inlet, passages connecting said suction pipe and said higherpressure inlet to ac said cylinder, an auxiliary passage connecting theortions of the cylinder on both sides of the piston, and a valve openingcommunication through said auxiliary passage when the piston is broughtto retracted position. 19. In vacuum brake mechanism for automotivevehicles provided with an internal combustion engine having a throttlecontrolled suction passage, the combination with a part to be actuated,an actuator for said so partincliuding a cylinder and a piston movabletherein, passages leading to and from said cylinder for conveying motivefluid to opposite sides of the piston to actuate the same, valves forcontrolling said passages 85 an auxiliary passage connecting both ends 0the cylinder to equalize pressures on opposite sides of the piston, anda separate valve for controlling-said auxiliary passage 20.- In a poweractuator, the combination so of acylinder closed at both ends, a doubleacting piston in said cylinder, reversing valve mechanism including asuction chamber, passages connecting said suction chamber with thecylinder on both sides of the piston, an air inlet, passages connectingsaid inlet with the cylinder on both sides of the piston, andcontrolling valves for said passages, means for connecting said suctionchamber with a v source of suction, means operable when the so piston isin retracted position for connecting the portion of the cylinder on oneside of thepisto'n only with said suction means, and an auxiliary meansfor connecting suction to said portion of the cylinder with the cylinder55 on the opposite side of the piston when the piston i s*brought toretracted position In testimony whereof we afix our signatures CALEB S.BRAGGP VICTOR W. IESRATHv

